Segmented grinding roll assembly



1953 'r. B. HAMILTON ETAL 3,409,235

SEGMENTED GRINDING ROLL ASSEMBLY Filed Dec. 21, 1965 2 Sheets-Sheet l FIG. I

INVENTORS THOMAS B. HAMILTON LORENZ J. ANDRESEN ALEXANDER BOGOT ATTORNEY Nov. 5, 1968 T. B. HAMILTON ETAL 3,409,236

SEGMENTED GRINDING ROLL ASSEMBLY 2 Sheets-Sheet 2 Filed Dec. 21, 1965 FIG. 3

e INVENTORS THOMAS B. HAMILTON LORENZ J. ANDRESEN ALEXANDER BOGOT BY W a! 0% ATTORNEY FIG. 2

United States Patent 3,409,236 N SEGMENTED GRINDING ROLL" ASSEMBLY Thomas B. Hamilton, Arlington Heights; Lorenz J. 1 Andresen, Chicago, Ill., and Alexander Bogot, West Hartford, Conn., assignors to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Dec. 21, 1965, Ser. No. 515,375

2 Claims. (Cl. 241-232) ABSTRACT OF THE DISCLOSURE Apparatus for pulverizing coal including a bowl and a cooperating roller between which the coal is pulverized. The roller is made up of a number of pieces or segments, which segments are secured to an inner cylindrical member by means of nuts and bolts. The heads of the bolts are cast integrally with the segments. Malleable metal washers are positioned between each segment and the inner cylindrical member to insure a tight fit between the segments and member.

This invention relates to apparatus for pulverizing material, and in particular to an improved grinding roll which coacts with a ring or bowl to perform the grinding action.

Many pulverizing mills today utilize a rotating bowl or table having a race or grinding surface upon which one or a number of rolls rotate, to thus pulverize coal or other material to a given degree of fineness. It has been found that considerable wear in these mills occurs on the grinding rolls, and these rolls must be periodically and frequently replaced. Because of the size these rolls are attaining today, being of one-piece forged or cast construction, a considerable cost is involved in replacing them. Also, the replacements result in periodic and lengthy shutdown periods for the entire mill, which are costly.

It is an object of our invention to provide a grinding roll for a pulverizing mill constructed in such a manner that it will have a long life, and will be easily and quickly replaceable when it does become worn.

Other objects and advantages will become apparent from the following description of an illustrative embodiment of our invention when considered with the accompanying drawings, wherein:

FIGURE 1 is a cross-sectional side view of a bowl mill embodying our invention;

FIGURE 2 is an enlarged cross-sectional view of the grinding roll shown in FIGURE 1; and

FIGURE 3 is an end view of the grinding roll taken on line 33 of FIGURE 2.

Looking now to FIGURE 1, numeral designates a bowl mill for grinding coal or other material therein. Inside the housing is positioned a rotatable bowl or table 12, mounted on shaft 14. Shaft 14 along with the attached bowl is rotated by means of worm wheel 18, which engages worm '16, mounted on a motor driven shaft.

One or more grinding elements or rolls are rotatably mounted on shafts 22. Adjustable spring 24 urges roll 20 towards the inner surface of the grinding n'ng.

Coal to be pulverized is introduced into the mill through inlet 36. Air enters through opening 26, and flows through annular space 32 to convey the ground material passing over the lip upwardly through the mill interior and into the classifier 30. The air and coal enter the classifier through inlets 28. The larger particles of unground coal fall back onto the grinding surface through bottom opening 34 for further grinding, and the finer particles carried along by the air are discharged through outlets 38.

Removable plate 39 is provided for the purpose of permitting access to the housing interior," and to enable the grinding roll assembly tobe removed'therefrom when replacement of the roll becomes necessary.

"Looking now to FIGURES 2 and 3, the details of the improved grinding roll can be more easily seen. The grinding roll assembly 20 is rotatably mounted on central shaft 22. Bearing or journal 40 is mounted on central shaft 22 so as to be immovable longitudinally along the shaft. Journal housing 41 surrounds the journal, and sleeve 42 is concentric with respect to housing 41.

Secured to sleeve 42 are a plurality of segments 44 which make up the grinding surface of the roll assembly. Each segment 44 is of one-piece cast construction, and two bolts 46 have their heads imbedded within segments at the time of casting. The threaded portions of the bolts 46 extend through openings in sleeve 42. The segments 44 are secured to sleeve 42 by means of nuts 48 which are tightened on the bolts. These nuts 48 are located in annular grooves 50 contained on the inner surface of sleeve 42.

A copper, or other malleable metal washer 52 is positioned between segments 44 and sleeve 42, surrounding each bolt 46. Lock washers 54 are also provided for each nut.

The entire roll assembly, including sleeve 42, is slipped over the bottom end of journal housing 41, and secured in place by means of nut 56, which is threaded onto threads 58 on the end of sleeve 41.

As seen in FIGURE 3, there is a slight space 60 between each segment 44, in the assembled position. This slight spacing is necessary in order to insure the ready assembly of the segments into a completed roll assembly, regardless of any slight irregularities on the individual segments, which are of one-piece cast construction. These segments are not machined at all, and there are always some small irregularities on any cast member. These spaces 60 will fill with coal dust soon after the roll is initially put into operation, and thus will not present a great problem during later operation.

The malleable washers 52 will ensure a good fit between the segment and the sleeve 42 regardless of any slight irregularities on the inner surface of the cast segments. Because these segments are of one-piece cast construction, and do not need any machining done to them at all, it is possible to make these members of a very hard material having extremely good abrasive resistant characteristics. The metal used can have a hardness on the order of Rockwell hardness No. 75. A typical material that can be used is Nihard or Diamite."

While we have illustrated and described the preferred embodiment of our invention, it is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made therein without departing from the spirit and scope of the invention. We therefore do not wish to be limited to the precise details set forth but desire to avail ourselves of such changes as fall within the purview of our invention.

What we claim is:

1. In a grinding mill, a grinding ring, a grinding roll which coacts with the ring to perform the grinding action, means for imparting relative rotation between the grinding ring and grinding roll, a shaft upon which the grinding roll is mounted, a journal surrounding the shaft, a first member surrounding the journal, thus being rotatably mounted on the shaft, a second member surrounding said first member, said second member being made up of a plurality of unmachined, one piece cast construction metallic segments, which when secured to the first member in side-by-side relationship, form a grinding 3 4 surface which coacts with the grinding ring to perform References Cited 7 the desired grinding, each of said segments containing UNITED STATES PATENTS plural bolt means the heads of WhlCh are cast integral with the segment, the threaded end of each bolt means 9331603 9/1909 Wagg "'1 1 7 9 X passing through an opening in the first member, and nut 5 2294'098 8/1942 Stromer ""f 4 'means for securely fastening each segment securely to 3,138,337 6/1964 Bogot, e 4 9 the first member.

2. The combination set forth in claim 1, wherein a GERALD DOST Plimary Examiner malleable metal washer surrounds each bolt means and R. J. ZLOTNIK, Assistant.Examiner. is positioned between each segment and the first member. 10 

